AM radio to lose hiss and crackle

A digital radio technology that promises to banish hiss and crackle from AM broadcasting has been given its first public demonstrations by engineers.

Backed by major international broadcasters including the BBC World Service, Digital Radio Mondiale (DRM) gives near-FM quality to long, medium and short-wave radio transmissions.

The new standard is widely seen as vital to ensuring that AM radio – still the only option in many parts of the world – is not left behind as other broadcast media switch to digital formats.

Engineers from the broadcast division of Thales, one of the leading players involved in developing DRM, staged live short-wave transmissions in the US and China in the last few weeks.

The system, due for launch in mid-2003, applies technology similar to that used for digital terrestrial TV to radio frequencies in the sub-30MHz range. It uses advanced audio coding to eliminate the interference and variability associated with analogue AM services. It also offers advanced features such as automatic tuning and can transmit text-based data such as station information.

Digital Audio Broadcasting (DAB), the digital radio standard already widely used around the world, is a highly effective audio standard for broadcasting locally to densely populated areas.

But international radio services such as the World Service, or national broadcasters serving huge regions of Africa or Asia, will continue to need the range offered by sub-30MHz frequencies.

John Sykes, head of transmission services at BBC World Service, said DRM would mark a ‘dramatic leap forward’ for the range and quality of services broadcasters are able to provide. ‘As a casual listener you would probably think it was an FM broadcast, the quality is so good,’ said Sykes.

It has the added advantage of using existing frequencies and requiring a relatively low investment to upgrade existing transmitters.

‘DRM is an extremely cost-effective and elegant way to transform our service from something that is frankly a bit mid-20th century into one that is extremely up to date,’ said Sykes.

The consortium that has developed DRM is also keen to make receivers affordable, a major factor if the standard is to become established as a mass-market technology.

Sykes stressed the importance of DRM as a way of preventing AM broadcasting – and SW in particular – from becoming an ‘analogue backwater’ seen as inferior to newer transmission technologies.

Alongside the BBC World Service, the consortium behind DRM includes Voice of America, Voice of Russia, Radio Netherlands, Radio France Internationale and Radio Canada. Technology partners include Thales, Deutsche Telecom, Sony, JVC and Hitachi.